1. Field of the Invention
This invention is directed to a nozzle drive propulsion assembly for high performance operation of a marine craft and includes a propeller mounted on a distal end of a propeller shaft and surrounded by an annularly configured nozzle and supported by a strut assembly. Components facilitating and directional travel of the marine craft include a thrust mechanism, a rudder assembly and a deflector structure all connected to the nozzle downstream of the propeller and in interruptive relation to the flow of water issuing from the nozzle.
2. Description of the Related Art
Marine propulsion systems vary greatly in both structural and operational features dependent in large part on the intended function and operation of the marine craft, with which they are used. The broad categories of marine propulsion systems incorporating a propeller drive include inboard drive systems, outboard drive systems and a combination or inboard/outboard propulsion units. Historically, propeller drive is perhaps the most commonly used mechanical means of propelling a craft through the water. As such, it is known to provide a shroud or substantially protective structure used in combination with the rotating propeller. Basic to all such shrouded propeller assemblies and at the core of associated propulsion systems is the existence of the shroud or nozzle housing itself. This basic concept was developed by an individual named “Kort” during the mid 1920's. Due to their popularity, shrouded propeller assemblies have been used extensively throughout the years in a variety of different forms and are commonly referred to as Kort nozzles.
Since its conception the Kort nozzle assembly has been extensively modified so as to adapt shrouded propulsion systems to particular categories of marine craft and their intended function, as set forth above. Even earlier than the extensive implementation of the Kort nozzle into marine propulsion systems, as currently contemplated, various protecting devices have been used in combination with the propeller. Such known devices include a basic hollow cylinder used in combination with a propeller being structured to serve as a maneuvering mechanism for an inboard motor.
In addition to the above, it is universally accepted that propellers are an integral part of outboard motor drive systems which are primarily intended to propel a variety of different smaller water craft. However, it was quickly discovered that an unguarded propeller, when rotating at high speeds, is frequently subjected to extensive and sometimes irreparable damage. Accordingly the use of the Kort nozzle, as well as other types of propeller shrouds was initially used to provide protection to the rotating propeller. More currently, the advancing technology in marine craft has led to structural modifications aimed at developing increased thrust while still incorporating the basic structure of protective propeller shrouds. In spite of the various attempted structural modifications, the resulting operative features are normally productive only in a relatively limited performance range such as the development of sufficient thrust to allow travel of a water craft at up to approximately 12 knots. As such, shrouded propellers incorporating a nozzle type structure are commonly used on heavy-duty water craft such as tug boats, towing barges, etc.
Accordingly, there is a recognized need in the marine industry for an efficient, effective propulsion system preferably incorporating the advantages offered by a shrouded propeller assembly and including structural modifications beyond those used in known propulsion systems. Further, such an improved propulsion system should have an extended operable life and be readily adaptable for use on a variety of different water craft, while still accomplishing sustained, high performance operation at speeds not previously contemplated.